Compressor apparatus



Feb. 18, 1947.

A. H. REDDING 2,415,847

COMPRESSOR APPARATUS Filed May 8, 1943 2 Sheets-Sheet 1 as H 5.

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INVENTOR Rmvou: H. REDDINQ.-

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ATTORNEY Feb. 18, 1947. REDDlNG 7 2,415,847

COMPRESSOR APPARATUS Filed May 8, 1943 2 Sheets-Sheet 2 Fig. 13. F'IG-14.

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BY 1 w, ATTORNEY Patented Feb. 18, 1947 UNITED STATES PATENT OFFICE2,415,847 COMPRESSOR APPARATUS Arnold H. Bedding, Swarthmore, Pa.,asslgnor to WestinghouseElectric Corporation, East Pittsburgh, Pa., acorporation of Pennsylvania Application May 8, 1943, Serial No. 486,142

Claims. 1

This invention relates to axial-flow compressors or blowers and thelike, and particularly to improved blading therefor and the method ofmaking the same, and it has for an object to, provide an improved methodand device of the character set forth.

It is also an object of the present invention to provide blading forapparatus of the character set forth which is relatively easy tomanufacture.

Blading for high eiiiciency compressors has required complicated forgingand machining operations which are time-consuming and require a highdegree of skill. In accordance with the present invention, an airfoilblade is provided which is eflicient and requires but a few simplemachining operations in its manufacture.

While the compressor and blading therefor to be hereinafter described isparticularly adapted for use with and to be driven by a high-speed gasturbine, it will be apparent to those skilled in the art that theinvention is not limited to this particular application.

These and other objects are effected by the invention as will beapparent from the following description and claims taken in connectionwith the accompanying drawings, forming a part of this application, inwhich:

Fig. l is a side elevational view of an axial-flow compressorincorporating the present invention, portions being broken away for thesake of clary;

Fig. 2 is a plan view of a portion of one of the rotors of thecompressors shown in Fig. 1;

Fig. 3 is a sectional view taken substantially on the line III-III ofFig. 2;

Figs. 4, 5, 6, 7 and 8 are sectional views taken substantially along thelines IV-IV, VV, VIVI, VII-VII and VIII-VIII, respectively, of Fig. 3;

Fig. 9 is a fragmentary view showing a portion of one of the compressorrotor hubs and blades attached thereto;

Fig. 10 is a fragmentary view of a portion of one of the rows ofstationary guide vanes of the coinpressor;

Figs. 11 and 12 are sectional views taken substantially on the linesXIXI and XII-XII, respectively, of Fig. 2, and drawn to a smaller scale;

Figs. 13, 14 and 15 are views, in perspective, of one of the blades ofthe compressor and showing schematically a jig on which the blade ismounted for finishing the convex surface thereof; and

Figs. 16 and 17 are views similar to Fig. 15, illustrating twomodifications of the invention.

Referring to the drawings, the compressor, generally indicated I0, is ofthe rotary axial-flow type, It comprises an outer casing structure II inwhich is journaled a shaft I2 having one or more hubs or discs l3carrying rows of rotor blades M which cooperate with intervening rows ofstationary blades or vanes l5. Air entering the intake I6 is directed bythe stationary guide vanes ll fixed to the casing for axial-bowcompression in successive stages by the rows of blades and vanes l4 andI5.

The present invention is particularly suitable for use with a high-speedgas turbine power plant, such as employed in the propulsion of aircraft,and, consequently, must be of minimum weight while capable of operatingsafely at extremely high speeds which may be as high as 20,000 R. P. M.or higher. The improved compressor, while preserving high efficiency,employs rotor blades and stationary guide vanes which are of minimumweight and easily shaped without the use of elaborate jigs orcomplicated machining operations.

The rotor blades l4 have an integral root section IQ of rounded section,permitting the same to be anchored in complementary-shaped recesses 20formed in the rotor hubs. The intermediate guide vanes l5, which areshaped like the rotor blades, are provided with integral tenons 2| ateach end, secured in spaced holes provided in concentric split rings 22.These rings support the vanes and are in turn mounted in the casing H ina known manner.

The working portion of the rotor blades and of the guide vanes issubstantially segmentshaped in cross section throughout its length. Therear face 23 of each blade, hereinafter referred to as the convex face,is substantially an element of a cylinder or a cone, which is preferablymodified as hereinafter pointed out. The forward or leading face 24,hereinafter referred to as the chordal face, comprises a surface made upof chords of the cylinder.

To obtain high efficiency, it is desirable that the rotor blades bewarped from root to tip to correct for the change in direction of flowand velocity of the air from the root to tip at the entering edge 25 ofthe moving blades. It is also desirable that the cross-sectional area ofthe blades decrease from root to tip so that weight of the bladedecreases from root to tip to maintain a more uniform stress on accountof centrifugal force.

The convex face 23 of each blade is preferably anticlastic or concavefrom root to tip, as shown particularly in Fig. 15, while the chordalface 24 is a helical surface generated by a straight line traveling in ahelical path about an axis26 (Figs. 2 and 14) lying in the chordal face.As will appear later, the centers of gravity of the blade sections fromroot to tip lie in a line normal to the axis of rotation of thecompressor. The axis 2-5 of the blade is parallel to this line.

The rotor and stationary blades are identical a lathe, while the root IQof a rotor blade may be milled. It will be understood that the tenons 2|and root is may be formed before or after the finishing of the bladeproper.

As shown particularly in Fig. 2, the rotor blades [4 projected on theroot l9 lie entirely within the root.

Io shape the chordal face 24 of the blade, the blank is mounted in asuitable fixture on a milling machine which rotates the blank about theaxis 26 as it moves under the cutter. As the blank moves past themilling cutter, it is rotated by the fixture about this axis through anangle A, Fig. 2, to provide the warped chordal face 24.

The convex surface 23 of the blade is formed by mounting one or more ofthe blade blanks on a lathe fixture 28, shown diagrammatically by dottedlines in Figs. 13 to 15, inclusive, with the flat or chordal face 24 ofthe blank disposed inwardly. The blank is secured to the fixture so thatthe axis 26 of the helix of the chordal face is inclined away from theaxis of rotation of the fixture from the root to the tip of the blade,and inclined toward the leading edge of the blade from the root to thetip of the blade. The fixture is then placed in a. lathe and the convexsurface is formed by turning a cylindrical surface on the blank so as tohave the appearance illustrated in Figs. 13 and 14.

By inclining the axis 26 of the helix with respect to the axis ofrotation of the lathe fixture, the chordal face of the blade is inclinedtoward the convex face, from the root to the tip, resulting in adecrease in the cross-sectional area and weight of the blade from theroot to the tip.

It is desirable, although not necessary, to have the convex surface ofthe blade slightly concave in a longitudinal direction in order to keepthe centers of gravity of the cross-sectional areas from root to tipsubstantially in a straight line normal to the axis of the compressorhub l3. This may be accomplished by means of a grinding wheel 3|, shownin Fig. 15, having a cutting face 32 shaped to grind the desiredconcavity. The wheel is rotated against the rotating fixture and blankproducing the concavity 33 in the convex face of the blade.

The modified blades 34 and 35 shown in Figs. 16 and 17, respectively,differ from the blade described above in that the convex faces areelements of cones rather than of a cylinder. The blades 34 and 35 aremade in exactly the same manner as the first blade except that inturning the convex face they are mounted on fixtures, shownschematically at 36 and 31, respectively. The fixtures are placed in alathe and the convex surface formed by turning a conical surface on eachof the blanks so that these blades have the appearance shown in Figs. 16and 17.

The blade 34 is turned so that its convex surface is an element of acone whose diameter decreases from the root to the tip of the blade. Byforming the blade 34 in this manner, the chordal width of the blade tipis substantially less than the chordal width at the root of the blade,but the tip thickness may approximate the root thickness.

The convex surface of the modified blade 35 is an element of a conewhose diameter increases from the root to the tip of the blade. Byforming the blade in this manner, the chordal width at the blade tip mayapproximate the chordal width at the root of the blade and the thicknessof the blade at the tip is substantially less than at the root.

It is to be understood that in forming each of the blades 34 and 35, allof the steps in making the blade shown in Figs. 13 to 15 are employed.The chordal face of these blades is helical but, as mentioned above, theconvex surfaces are elements of cones rather than of a cylinder.

It is to be understood that one or more blanks may be mounted on thefixtures described above so that one or more blades may be formed in oneoperation.

While the invention has been shown in several forms, it will be obviousto those skilled in the art that it is not so limited, but issusceptible of various other changes and modifications without departingfrom the spirit thereof, and it is desired, therefore; that only suchlimitations shall be placed thereupon as are specifically set forth inthe appended claims.

What is claimed is:

1. In an axial-flow compressor or blower, blading wherein each blade isof circular segment section from the root to the tip, has a convex facewhose root and tip radii are the same and has a chordal face inclinedtoward the convex face from the root to the tip.

2. A blade as recited in claim 1 whose convex face is of uniform radiusfrom the root to the tip.

3. A blade as recited in claim 1 whose convex face has graduallydecreasing radii from the root to an intermediate section and thengradually increasing radii from the latter to the tip.

4. In an axial-flow compressor or blower, blading wherein each blade hasa convex face and a chordal face, said convex face being an element of aconical surface and said chordal face being generated by a straight lineintersecting said conical surface and moving in a helical path from theroot, to the tip of the blade 5. In an axial-flow compressor or bloweras set forth in claim 4 wherein the conical surface is of increasingdiameter from the root to the tip of the blade.

6. In an axial-flow compressor or blower as set forth in claim 4 whereinthe conical surface is of decreasing diameter from the root to the tipof the blade.

7. In an axial-flow compressor or blower, blading wherein each blade isof substantially segment section from the root to tip, has a chordalface, and has a convex face which is an element of a surface ofrevolution generated by a curved line moving in a circular path about anaxis disposed in the plane of the curved line, said curved line beingconcave with respect to said axis.

8. In an axial-flow compressor or blower, blading wherein each blade isof substantially segment section from the root to the tip, has a convexface which is an element of a surface of revolution generated by acurved line moving in a ment section from the root to the tip, has aconvex face which is an element of a surface of revolution generated bya curved line moving in a circular path about an axis disposed in theplane of the curved line, said curved lin being concave with respect tosaid axis, and has a chordal face which is inclined toward the convexface from the root to the tip and which is generated by a straight linemoving in a helical path from the root to the tip, the axis of saidhelical path being disposed at an angle to the first-mentioned axis.

10. In an axial-flow compressor or blovfr, blading wherein each bladeincludes a root for securing the same in the compressor and has a bodyportion of segment section from the root to the tip, the body portionhas a convex face and a chordal face inclined toward the convex facefrom root to the tip, and whereinthe projection of said body portionlies entirely within said root.

ARNOLD H. REDDING.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Kohler Dec. 13, 1932

